In the fabrication of integrated circuits on substrates, such as semiconductor wafers, the vapor deposition of chemicals, such as chemical vapor deposition (“CVD”) and atomic layer deposition (ALD), is often desirable. The expansion of suitable source chemicals has increasingly led to use of precursor materials that are naturally liquid or solid at room temperature and atmospheric pressure.
In order to effectively deposit using precursors from a solid or liquid source material, the solid or liquid source material must be vaporized first. In pursuit of this goal, evaporation apparatuses are used to effectuate the vaporization of a solid or liquid source material. In addition, heat sources are often employed in conjunction with such an apparatus in order to increase the vapor pressure above the solid or liquid source material.
Unfortunately, existing semiconductor processing systems, of which an evaporation apparatus is a component, have a number of shortcomings. For example, an evaporation apparatus for subliming a solid source material or vaporizing a liquid source material may offer both an inadequate ratio of solid or liquid source surface area to the desired vapor volume, and poor carrier gas/source material contact time. Often, current processing systems can allow a carrier gas to flow from inlet to outlet without intimately contacting the source material, thus preventing the carrier gas from becoming saturated with precursor vapor.
In certain instances, a large amount of precursor vapor is needed for deposition, such as batch-type deposition. In addition, deposition on a substrate having three-dimensional topology needs a large amount of precursor for a short period of time. Thus, there is a need for an evaporation apparatus that efficiently converts a solid or liquid source material into gas phase.